Compressor deicing and thrust balancing arrangement



May 22, 1956 P. P. NEW-COMB COMPRESSOR DEICING AND THRUST BALANCING ARRANGEMENT Filed April 14, 1950 w 2 MM w w 5 v E M I k H W 4 l a 6 6\ l./Y f i 4 1 g y r Z N IIIIIIIFPJ w m w WW M 0 6 z INVENTQR' PHILIP P. NEWCOMB BY WWW ATTORNEY United States Patent COMPRESSOR DEICING AND THRUST BALANC- ING ARRANGENIENT Philip P. Newcomb, Manchester, Conn., assignor to United Aircraft Corporation, East Hartford, Conn., a corporation of Delaware This invention relates to axial flow compressors and particularly to an arrangement for minimizing icing at the compressor inlet.

When the compressor is operating under conditions that will produce icing, the collection of ice at the compressor inlet can quickly cause serious restriction of the airflow and in the case of a compressor forming a part of a gas turbine power plant the restricted flow may result in an overheated turbine or the loss of so much power that the power plant will not continue to operate. Prior to my invention, air has been bled from the compressor after it has been compressed and heated, and this air has been discharged directly into the compressor inlet air. This arrangement requires that all of the entering air be heated thereby reducing the compressor efliciency by raising the inlet air temperature. A feature of this invention is the localized heating of the inlet ends of the struts or guide vanes at the compressor inlet by compressed air bled into the vanes from the compressor thereby minimizing the amount that the inlet air is heated and at the same time applying the heat where it is the most effective.

The compressed air which has been used for heating the guide vanes may be disposed of by bleeding it into the airstream and into the compressor since its pressure is considerably higher than the inlet air surrounding the vanes. A feature of this invention, however, is the use of the compressed air in counter-balancing the axial thrust on the compressor rotor by discharging the air from the vanes into a chamber one wall of which is formed by the inlet end of the rotor.

Other objects and advantages will be apparent from the specification and claims, and from the accompanying drawings which illustrate an embodiment of the invention.

Fig. 1 is a longitudinal sectional view through the compressor.

Fig. 2 is a fragmentary sectional view on a larger scale showing the flow of the air against the inner surface of the guide vane.

Referring to Fig. 1 the compressor has a casing 2 supporting spaced rows of stator vanes 4 which alternate with radially extending rows of compressor blades 6 carried by the rotor 8. The inner ends of the stator vanes carry seals 10 which cooperate with parts of the rotor to prevent leakage of air around the ends of the vanes.

The rotor is supported in predetermined relation to the casing by bearings 12 and 14 at the inlet and discharge ends of the compressor. The bearing 12 is supported by supporting means in the form of a diaphragm 16 extending inwardly from the inner wall 18 of the air inlet passage 20. Inlet guide vanes or supporting struts 22 extend transversely of the passage 20 and it is on these vanes that the formation of ice first occurs.

At the downstream end of the compressor the bearing 14 is supported by diaphragm 24 which extends in wardly from a ring 26 supported by a series of vanes 28. The outer ends of the vanes 28 are supported in a part of the casing 2.

2,746,671 Patented May 22, 1956 Air from a point adjacent the high pressure end of the compressor is withdrawn through a port 30 and delivered through a duct 32 to the hollow inlet guide vanes 22. It will be understood that a manifold ring 34 extending around the compressor casing forms an annular passage around the compressor for distributing the high pressure air which has been heated during the compression process to the several inlet guide vanes. The hot air entering these vanes raises the temperature of the vanes enough to melt the ice as it forms on the vanes or may in certain instances keep the vanes at such a temperature that the ice will not begin to form. Air escapes from the vanes through passages 36.

Referring now to Fig. 2, the thickest icing generally occurs on the leading edges of the guide vanes and accordingly the hot air entering the guide vane through a pipe 38 communicating with the manifold 34 is blown against the inside surface of the guide vane at its leading edge by radially arranged openings 40 in a tube 42 supported by the casing and positioned radially within the vane. With this arrangement the hottest part of the guide vane is the leading edge where icing occurs most rapidly although the remainder of the vane is warmed by the warmed air within the vane as it flows away from the leading edge. It will be understood that if icing occurs most rapidly on another part of the vane, the tube would be so located as to flow the hot air against this part.

The loads on the rows of compressor blades 6 develop an axial thrust on the rotor in the direction of the arrow 44, Fig. 1, and this thrust is also increased by the pressure loading on the downstream end of the compressor rotor in the chamber 46 since high pressure air from the compressor leaks directly into this chamber through the space 48 between the rotor and the ring 26. This thrust may be counterbalanced at least in part by causing the air escaping from the vanes 22 to be discharged into a chamber 50 at the inlet or upstream end of the compressor rotor. This chamber is defined, as shown, by the diaphragm 16, a part of the inner wall 18 and the upstream end of the compressor rotor. The end wall of the rotor consists of the portion of the first rotor disc 60 outwardly from the spacing flange 58, to the seal 52, the flange 58 on the inside of the first rotor disc and the end bell 56. The space between the end of the inner wall 18 and the rotor is closed by a plurality of seals 52 and another seal 54 closes the space between the rotor and the diaphragm 16 at its inner end to limit the leakage of air at this point. The pressure is thus contained within the chamber 50 except for such leakage that occurs at the seals. The leakage at the seals 52 may be controlled as by selecting the spacing of the fins forming part of the seal from the adjacent sealing surface, so as to permit the necessary flow of air through the inlet vanes for preventing the accumulation of ice. It may be noted that air will not leak through the compressor since the end bell 56 forming a part of the rotor prevents the flow of air axially through the rotor. It will be understood that the spacing flange 58 between the outer edge of the end bell and the adjacent rotor disc 60, that is, the first disc, forms a continuous annular ring concentric to the axis of the rotor thereby forming a complete enclosure for the chamber 50 at this point. Together, end bell 56, flange 58, and first disc 60 form a balance piston which is urged to the right by the pressure in chamber 50 to partially compensate for the axial thrust 44.

It is to be understood that the invention is not limited to the specific embodiment herein illustrated and described, but may be used in other ways without departure from its spirit as defined by the following claims.

I claim:

1. An axial fiow compressor including a casing having means thereon forming an annular passage therewith, hollow inlet guide vanes extending from said casing and at least one stage of compression downstream of said vanes, in combination with means receiving air from said compressor and connected to said casing, said last means communicating with said passage for discharging into said passage a portion of the compressed air from the compressor, a tube positioned within and surrounded by each hollow vane and communicating with the passage to receive air therefrom, said tube having openings therein for directing fluid from said tube against a selected portion of the inner surface of the surrounding hollow vane, and means venting each of said vanes.

2. An axial flow compressor including a casing having means thereon forming an annular passage therewith, hollow inlet guide vanes extending from said casing and at least one stage of compression downstream of said vanes, in combination with means receiving air from the compressor and connected to said casing, said last means communicating with said passage forming means for discharging into said passage a portion of the compressed air from the compressor, a tube positioned within and surrounded by each hollow vane and communicating with the passage to receive air therefrom, said tube having at least one row of forwardly directed openings References Cited in the file of this patent UNITED STATES PATENTS 2,333,053 Stroehlen Oct. 26, 1943 2,429,681 Griffith Oct. 28, 1947 2,441,135 Chalupa May 11, 1948 2,446,663 Palmatier Aug. 10, 1948 2,462,600 Boestad et a1 Feb. 22, 1949 2,469,375 Flagle May 10, 1949 2,474,068 Sammons et a1. June 21, 1949 2,474,258 Kroon June 28, 1949 2,477,798 Griffith Aug. 2, 1949 2,599,470 Meyer June 3, 1952 FOREIGN PATENTS 237,475 Switzerland Sept. 1, 1945 619,390 Great Britain Mar. 8, 1949 629,044 Great Britain -2 Sept. 9, 1949 897,709 France June 5, 1944 

